1959 Johnson Seahorse 18HP w/electric start

[Big Johnson31]

We this is my first post. I have read alot of good info from this site the last year or so and just now decided to become a member.

My question is. I just bought a 1959 Johnson Seahorse 18HP w/electric start. It has great compression and has been sittin in a barn for quite some time. Everything is very clean and in great shape. The probelem is I dont know how to test this engine because i dont have the right power supply hookup for it or the right type of fuel line hookup. I dont want to damage anything by rigging power or fuel to it.. So I need to know the best way to test this engine.

Thanks

 

[Big Johnson31]

Re: 1959 Johnson Seahorse 18HP w/electric start

I was also told it takes a pressurized tank. Is this true?

 

[stingertrey]

Re: 1959 Johnson Seahorse 18HP w/electric start

You will need a dual line fuel tank.. I thnk 59 was the last year for these.. at 60 they went to a single fuel line with a fuel pump. You should have a bubble on the top of the tank that you pump to prime the engine.. as for the electronics im unsure

 

[Big Johnson31]

Re: 1959 Johnson Seahorse 18HP w/electric start

I had just found that out on the pressure tanks... Man thats just my luck to get a motor 1yr behind the single line.. I just bid on two on ebay. One is local so I might beable to wheel and deal there.. Thats for your help though.

 

[Big Johnson31]

Re: 1959 Johnson Seahorse 18HP w/electric start

Ok, after more and more reading I feel it would be best and safer to convert this motor to a single line.

So On that note where do i begin to look for the power cable for this motor so i can use the electric start.

 

[lindy46]

Re: 1959 Johnson Seahorse 18HP w/electric start

Ok, after more and more reading I feel it would be best and safer to convert this motor to a single line.

So On that note where do i begin to look for the power cable for this motor so i can use the electric start.

Good luck on the wiring harness - they are somewhat hard to find. Check on Ebay or go to AOMCI.org and post a want ad. You may end up having to fabricate your own harness. Not too hard to do if you have a factory service manual with a wiring diagram.

 

[chucko]

Re: 1959 Johnson Seahorse 18HP w/electric start

converting to a single line is not hard, but why would you want to. If your stuck on the idea, youll need an expensive new pump, and the pressure take off from on the side of an 18 with the single hose pump, as well as the fittings and connector!. just keep your two hose job. Its very reliable. Count on doing everything to it, points, coils, pump kit, carb kit, and lower end seal kit. Do it over the winter. Its not difficult, and it will give you a chance to learn how simple and well built your 18 is. Have fun.

 

[samo_ott]

Re: 1959 Johnson Seahorse 18HP w/electric start

I have 2 electric start 18's and no wiring harnesses. They are hard to to find. I plan to make my own. it's only a few wires and a solenoid.

To test the starter, you only need to hook 12v up to the starter with jumper cables from a battery. Hook the last connection to the frame of the outboard as this is where it will spark.

 

[kbait]

Re: 1959 Johnson Seahorse 18HP w/electric start

Before you consider fuel side, actuate starter as above, or just pull the rope and check compression and spark (1/4" blue bolt needed). Then go from there. Ignition is the same as any 3-40 hp from '52-'70ish, so parts are readily available through this site at great prices..
Cool motor.. You'll like it!

 

[Big Johnson31]

Re: 1959 Johnson Seahorse 18HP w/electric start

Well priced what it should cost to convert it to a single line and it is around $75 to $100. I might be able to do it for less because I have alot of the materials needed already.. I just need to buy a fuel pump and new fitting on the motor side. As for the power cable. This is a task. But Im sure I will get it figured out. but expect me to come back with alot more questions..

 

[Big Johnson31]

Re: 1959 Johnson Seahorse 18HP w/electric start

Before you consider fuel side, actuate starter as above, or just pull the rope and check compression and spark (1/4" blue bolt needed). Then go from there. Ignition is the same as any 3-40 hp from '52-'70ish, so parts are readily available through this site at great prices..
Cool motor.. You'll like it!

Compression and spark are great. I dont have a tank but will just gravity feed it to test it breifly. but I have been told that pressurized tanks are very dangerous. My 13 yr old son takes the boat out with his cousins and right now it has a 65 Johnson 9.5 on it. I got the 18 HP for larger lakes but didnt realize it needed a pressurized tank. I cant complain for $50. Like I stated before it has been inside, covered and is very clean. But The guy I bought it from said it was gave to him for working on a car. I guess all thats left to do is test it and then figure out what needs fixing.

 

[steelespike]

Re: 1959 Johnson Seahorse 18HP w/electric start

Motor will test run without the harness.You can hand crank or jump start
as described. It should stop ok when you reduce the throttle.Nothing wrong with pressure tanks used them for years.They are pricey and the quick connect runs about $40 up.If you get a pressure tank be sure it has the connector.A working tank makes it easy just plug it in.
If the motor has sat around you will probably need to go through the fuel
system.

 

[lindy46]

Re: 1959 Johnson Seahorse 18HP w/electric start

I've had many a motor with pressure tanks over the last 40+ years - never had any problems with them. Not sure why they are considered dangerous other than gas under pressure. But there isn't that much pressure and it's a closed system, unlike a vented tank. Seems like there would be more danger of fire from fumes escaping a vented tank. Anyone know of any actual accidents/explosions/etc. with a pressure tank?

 

[coolguy147]

Re: 1959 Johnson Seahorse 18HP w/electric start

pressure tank is pretty good. i ahve a 1959 10hp with a pressure tank. maybe 30 bucks? probably less to rebuild gaskets and hoses worked great. i opened it up and cleaned all the rust out with the pressure washer which i believe is the safest other then the baking soda electric method.

electric is really needed on that motor. nice assessory but the motor is that tough to pull. if you had a 50's 35hp then its really is needed trust me

 

[samo_ott]

Re: 1959 Johnson Seahorse 18HP w/electric start

I've been using pressure tanks for years also without problem. I have never heard of an issue with them either although folks talk about it a lot.

You don't really need an electric start on an 18 though. They're very pullable.

As mentioned, if you get a pressure tank, make sure you get the connector. They are ~C$130 new in this area.

An 18hp is a pretty strong motor. I think I'd be leary about a 13 year old using one, but each is different.

 

[jbjennings]

Re: 1959 Johnson Seahorse 18HP w/electric start

I must add MY opinion:

The pressure tank danger is total nonsense.
If you want to convert it, I think it's a good idea, but not because the pressure tanks are dangerous. They all build up pressure if the vent is closed and they heat up in the sun. However, if the pressure tank heats up, the vent valve on the tank will let the pressure out. It only runs on about 8 psi and the only problem with it I can think of is if your connector o-rings are bad it could leak fuel out. That will be obvious, quickly.

A few questions:
Are you going to use remote controls on the motor?
If not, it's easy to set up a starter button on the motor and the wiring harness is incredibly easy to make and I'd be glad to help on that as are numerous others. If you want remote controls, it's equally as easy.
Your motor is a steal for $50----I'd pay that just for the starter and starter bracket. Do you have a starter solenoid? If not, they're cheap anyway.

I find the 18 hp evinrudes of any year to be pretty easy to pull start, and one running decently will start cold in 3 pulls or something is wrong with it or the starting procedure is wrong. The 25's from '53 and '54 are a bear to pull start!

Last of all, I think a lighweight teenager with a light aluminum boat with an 18hp is a FAST rig. I'd say possibly 28mph or faster.
Good luck,
JBJ

 

[Big Johnson31]

Re: 1959 Johnson Seahorse 18HP w/electric start

Im just a country guy and my boy is just as country as I am. Heck he drives the trucks all over the property. Even has LTZ400 fourwheeler. So Im not worried about the power of the motor. I trust he will use common sence when out on the water. hes a good kid. But i would like your help with the power supply. And yes it has the starter and stuff. Its not hard to pull at all just thought it would be a nice feature to have..
As for fuel. I guess I will buy a tank off ebay and use it untill it becomes any problem.

 

[coolguy147]

Re: 1959 Johnson Seahorse 18HP w/electric start

ya forgot to mention the pressure tank has a special relase valve. and its virtually no maitencee for the whole motor life. fuel pump is vibrating like thousands of times when running sooner or later you will have to pay money to replace.

and for any tank the vent should be open when not in but the pressure tank cap needs to be shut when being used by the way

safe boating

i have a 35hp on a 15foot booat and it does about 28-30mph. and trust me its pretty fast on the water. and that motor is a tiller! even more dangerous. when i 13 i wasnt very educated in boating and new thing for me by myself. and something very bad happened. of course my boat is remote so its much safer and easier to drive.

i would suggest to install a kill switch on the motor only about 10 dollars from the iboats store. good investment not hard to install. especially if your 13 falls out will save a lot of frustation. maybe even your sons life

safe boating